Q6-11.
You can decrease the specific gravity of a
battery holder (cradle) and the battery hold-down
lead-acid battery by performing which of the
device. Inspect the battery for a cracked or bulging
following functions?
case. Inspect the sealing compound on top of the
battery for leaks or cracks.
1. By changing the number of negative plates
in each cell
Remove the vent cap from each cell and check the
2. By removing a small amount of electrolyte
electrolyte level of the battery. Make sure the vents in
and replacing with distilled water
the vent caps are free of any obstructions.
3. By removing the vent caps to allow for
The state of charge and the ability of a battery to
evaporation of the electrolyte
withstand loads must meet the manufacturer's spec-
4. By changing the number of positive plates
ifications before you check any other part of an
in each cell
electrical system. The battery load test is recommended
by most battery manufacturers. This test indicates how
CHARGING SYSTEMS
well the battery can perform under normal cranking
load conditions. For example, take a 12-volt battery at
LEARNING OBJECTIVES: Identify the
70F. When a 300-amp load is applied for 15 seconds,
components of SE electrical charging systems.
the battery should produce 9.6 volts or better. If not, it
Identify procedures for inspecting, checking,
should be charged or replaced.
testing, and adjusting SE electrical charging
system components. Identify procedures for
For more information on servicing and main-
troubleshooting SE electrical charging system
tenance of batteries, refer to Naval Aircraft and Naval
components. Identify procedures for repairing,
Aircraft Support Equipment Storage Batteries,
removing, and replacing SE electrical charging
NAVAIR 17-15BAD-1.
system components.
Q6-7. How much voltage does each cell of a fully
The electric generator is the heart of the automotive
charged 12-volt battery produce?
charging system. By using the principle of magnetic
1.
1.85 Vdc
induction, the generator converts mechanical energy to
2.
2.0 Vdc
electrical energy. The electrical energy produced by the
3.
2.15 Vdc
generator recharges the battery and powers the entire
4.
2.5 Vdc
electrical system while the engine is running. The
Q6-8. What should the specific gravity reading be in
output of the generator must be regulated to prevent
a fully charged lead-acid battery?
system damage from overvoltage. A properly
maintained charging system improves the reliability of
1.
1.170 - 1.200
support equipment.
2.
1.205 - 1.230
3.
1.235 - 1.260
Two types of generators are used in automotive
4.
1.265 - 1.290
systems: the direct current (dc) generator and the
alternating current (ac) generator (alternator). The dc
Q6-9. Which of the following tools is used to
generator produces direct current to supply the
measure the specific gravity of a lead acid
electrical system's needs. It is controlled by a voltage
battery?
and current regulator. The dc generator is limited in its
1.
output capability at lower engine speeds.
2.
An ammeter
The alternator has the same function as the dc
3.
A hydrometer
generator, but since the battery charging system
4.
An electrometer
requires dc, the ac output of the alternator must be
Q6-10.
What type of gas is released from the negative
converted to dc. The output of the alternator produces
plates of a lead acid battery when it is being
enough power to fulfill the system's needs at all engine
charged?
speeds.
1.
DIRECT CURRENT (DC) GENERATOR
2.
Oxygen
3.
The essential parts of a dc generator are the
4.
Carbon monoxide
armature coil, the commutator with brushes, and a
6-14
